Method of making open hearth steel and flux employed in such method



Patented July 13, 1937 EEC METHOD OF MAKING OPEN HEARTH STEEL AND FLUX EMPLOYED IN SUCH NIETHOD Francis J. Whitaker, Youngstown, Ohio No Drawing. Application October 17, 1936, Serial No. 106,209

4 Claims.

This invention relates as indicated to an improved method for making open hearth steel and likewise pertains to an improved flux employed in practicing such method.

As is well known, open hearth steel, after being poured into the ingot and upon solidification, will, many times, be found to contain blow-holes and pipes generally resulting from the liberation of occluded gases during solidification of the steel.

It is a principal object of my invention to provide a method of making open hearth steel and an improved flux for use in such method which will produce a steel having an appreciably lesser tendency to form blow-holes and pipes in the ingot than any process heretofore employed.

Other objects of my invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims; and the following description sets forth in detail one method and products constituting, however, but one of various applications of the principle of my invention.

My invention may be broadly stated as comprising a new process of making open hearth steel characterized by the employment of a new flux which, when introduced into the steel prior to pouring into the ingot will result in a material reduction in the number of blow-holes and pipes formed in the ingot upon solidification thereof and accordingly the production of an improved and sounder steel.

More specifically, this invention comprises a process for making open hearth steel in which the flux added for the purpose of reducing the number of blow-holes formed is free from man ganese.

The following table gives the range of com position of the fiux comprising one feature of my invention and used in practicing the process of such invention:

Pounds No. 1--Sodium sulphide 8 to 12 No. 2Sodium nitrate 1.5 to 2.5 No. 3-Combination of No. 1 and No. 2 9.5to 14.5 No. 4-Ferrochrome 4% to 6% carbon69% to 70% chrome 2 to 4 No. 5-Ferrotungsten to W. 2 to 4 No. 6Fluor spar 40 to 60 No. 7-Calcined iron ore to 125 The flux in the form in which it is added to the bath in the furnace is prepared in the following manner:10 pounds of component No. 1 and 2 pounds of component No. 2 are well mixed and after mixture, slowly heated until substantially all of the moisture is driven off. Care should be exercised not to stir such mixture while it is being heated. After the moisture has been expelled from the mixture, it is permitted to cool and thereafter ground to a fineness which may be best described as that of medium ground cofiee. This ground mixture is component No. 3 in the previously given table.

A preferred composition of my improved flux is as follows:-All of component No. 3 produced in the manner previously described; 3 pounds of component No. 4; 3 pounds of component No. 5; 50 pounds of component No. 6; and pounds of component No. 7. All of the above quantities of the several components are well-mixed and then such mixture packaged in sheet metal containers, which each contain approximately 50 pounds of the mixture.

The containers with their contents are then introduced into the bath in the open hearth furnace under the slag at about one hour before the heat is tapped.

An open hearth steel of unusual strength may be produced if the proportional amounts of components Nos. 4 and 5 are increased and about one-third more than previously specified of No. 3 is employed. When the flux thus modified is employed, the carbon content of the steel should be slightly higher than normal.

The flux as above described, may be used in all grades of open hearth iron and steel with the proportional amounts of components Nos. 4 and 5 varied to produce particular conditions such as may be desired.

My improved flux may be employed in amounts from about 133.5 pounds to about 207.5 pounds for each 25 ton heat of steel.

An open hearth steel made in accordance with my improved process and by adding thereto my new fiux, as above defined, will be found to be exceptionally free from blow-holes and piping.

Other forms may be employed embodying the features of my invention instead of the one here explained, change being made in the form or construction, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed, whether produced by my preferred method or by others embodying steps equivalent to those stated in the following claims.

I therefore particularly point out and distinctly claim as my invention:-

1. As a composition of matter for use as an addition agent to open hearth steel, a mixture comprising the following:

2. As a composition of matter for use as an addition agent to open hearth steel, a mixture comprising the following:

Pounds 1Sodium sulphide 10 2-Sodium nitrate- 2 No. No;

No. 3-Combination of No. 1 and No. 2 12 No. 4-Ferrochrome 4% to 6% carbon- 69% to 70% chrome 3 No. 5- Ferrotungsten 65% to 70%W 3 No. 6--Fluor spar No. 7-Calcinad iron ore 105 3. In the method of making open hearth steel, the step of adding to the bath of steel in the open hearth furnace from about 5.34 pounds to about 8.03 pounds per ton of steel, a mixture comprising the following:

Pounds No. 1Sodium sulphide 8 to 12 No. 2Sodium nitrate 1.5 to 2.5 No. 3-Combination of No. 1 and No.2 9.5 to 14.5 No. 4-Ferrochrome 4% to 6% carb0n-69% to 70% chrome 2 to 4 N0. 5Ferrotungsten to W 2 to 4 No. 6-Fluor spar 40 to 60 No. '7-Calcined iron ore to 125 4. In the method of making open hearth steel,

.the step of adding to the bath of steel in the open hearth furnace from about 5.34 pounds to about 8.03 pounds per ton of steel, a mixture comprising the following:

Pounds No. 1-Sodium sulphide 10 No. 2-Sodium nitrate 2 No. 3-Combination of No. l and No. 2 12 No. 4-Ferrochrome 4% to 6% carbon- 69% to 70% chrome 3 No. 5-Ferrotungsten 65% to 70%W 3 No. 6-Fluor spar 50 No. 7-Calcined iron ore FRANCIS J. WHITAKER. 

